/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2009 by Red Hat Inc and/or its affiliates or by
 * third-party contributors as indicated by either @author tags or express
 * copyright attribution statements applied by the authors.  All
 * third-party contributions are distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.engine.jdbc;

import java.io.Reader;
import java.lang.reflect.Proxy;
import java.sql.Clob;

/**
 * Manages aspects of proxying java.sql.NClobs for non-contextual creation, including proxy creation and
 * handling proxy invocations.
 * <p/>
 * Generated proxies are typed as {@link java.sql.Clob} (java.sql.NClob extends {@link java.sql.Clob}) and in JDK 1.6 environments, they
 * are also typed to java.sql.NClob
 *
 * @author Steve Ebersole
 */
public class NClobProxy extends ClobProxy {
	public static final Class[] PROXY_INTERFACES = new Class[] { determineNClobInterface(), NClobImplementer.class };

	private static Class determineNClobInterface() {
		// java.sql.NClob is a simple marker interface extending java.sql.Clob.  So if java.sql.NClob is not available
		// on the classloader, just use java.sql.Clob
		try {
			return getProxyClassLoader().loadClass( "java.sql.NClob" );
		}
		catch ( ClassNotFoundException e ) {
			return Clob.class;
		}
	}

	protected NClobProxy(String string) {
		super( string );
	}

	protected NClobProxy(Reader reader, long length) {
		super( reader, length );
	}

	/**
	 * Generates a {@link java.sql.Clob} proxy using the string data.
	 *
	 * @param string The data to be wrapped as a {@link java.sql.Clob}.
	 *
	 * @return The generated proxy.
	 */
	public static Clob generateProxy(String string) {
		return ( Clob ) Proxy.newProxyInstance(
				getProxyClassLoader(),
				PROXY_INTERFACES,
				new ClobProxy( string )
		);
	}

	/**
	 * Generates a {@link Clob} proxy using a character reader of given length.
	 *
	 * @param reader The character reader
	 * @param length The length of the character reader
	 *
	 * @return The generated proxy.
	 */
	public static Clob generateProxy(Reader reader, long length) {
		return ( Clob ) Proxy.newProxyInstance(
				getProxyClassLoader(),
				PROXY_INTERFACES,
				new ClobProxy( reader, length )
		);
	}

	/**
	 * Determines the appropriate class loader to which the generated proxy
	 * should be scoped.
	 *
	 * @return The class loader appropriate for proxy construction.
	 */
	protected static ClassLoader getProxyClassLoader() {
		ClassLoader cl = Thread.currentThread().getContextClassLoader();
		if ( cl == null ) {
			cl = NClobImplementer.class.getClassLoader();
		}
		return cl;
	}
}
